For me, the most annoying limitation of the ZX80 and ZX81 BASICs is no multi-statement lines :( This is the apparent annoyance with ZX Spectrum BASIC (and all other variants except for ZX80/81 BASIC) because multi-statemented BASIC lines might make it more difficult to debug. Maybe, but this is how...

For me, the most annoying limitation of the ZX80 and ZX81 BASICs is no multi-statement lines :( A ZX Spectrum was the first computer in our house when I was young. At school I used Acorn BBC Model B machines. So I got into the habit of using the full screen width of a line (well, as much as possible...

Well, it does depend on which “ZX BASIC”! There have been three for Z80 based machines: BASIC for the ZX80 (4K byte ROM) BASIC for the ZX81, also available for upgrading a ZX80 (8K byte ROM) BASIC for the ZX Spectrum (16k byte ROM) [I’m not including the expansions to BASIC in the later 128k ZX Spec...

Err. How long have you got? There are rather a lot. One of the biggest, is the different string handling. Another biggie is the character sets, the ZX81 character set and codes being unique to it only. The Commodore character set and codes also being non-standard. The ZX Spectrum character set almos...

The ZX Spectrum 16k, 48k and Plus models all have a DC/DC converter/inverter power system on the main board to generate +12V and a -5V supply rails for the 4116 DRAM chips. The +12V is also used by the colour encoder chip (LM1889). Models using unmodified issue 1,unmodified issue 2, some issue 3 (un...

The ZX81 for sale in this thread is priced at £30.95 (plus postage). Using the exchange rate that Google uses gives a price of $40.11 USD (not including postage). Typical prices are around £20 to £40 for ZX81’s that are ‘untested’. Here is a link to eBay.co.uk showing actual selling prices. As you c...

(Glad I could flip the switch without power cycling and re-typing. It was only like a 6 line program, but still. ;-) ) And it looks like my switch worked! Yay! ;-) Yes, the Sinclair ROM code reads the 50/60Hz pin every time it generates a TV line. So if a switch is connected to this pin, you can sw...

893B2F76-B2C3-4241-A505-4069DF9B237C.jpeg BAC0334D-255C-4FCA-8A60-7E5FECD9BC8D.jpeg F586C1E8-496B-437F-A42B-C65039B7243C.jpeg BDFBF906-F15C-4507-B27F-28B1E25D4388.jpeg As you can see, the marks show up more on some cases, and on others are rather hard to see unless you catch the light the right way.

Good work on getting your Zeddie working :D :D :D The Sinclair 16k RAM packs are not very reliable these days. The chips used (4116 type 16k bit DRAM types or equivalents) need three supply voltages (+5V, +12V and -5V). Two of these are generated by a simple DC/DC converter/inverter circuit. The ele...